I just checked out bcrypt; pretty amazing. It encrypted a folder of 14 books in about 5 seconds, and restored in about a second.

Update: worked great unencrypting an encryped file passed to another linux computer with bcrypt installed (i.e., password goes with the file). I couldn't get the windows version to work at all, however.Wish it had a switch for encrypting subdirectories, but ./*/* works.